1. Field of the Invention
The invention relates to a metal forming tool.
2. Description of the Prior Art
A bangle bracelet is conventionally produced by drop-forging a strip of sheet stock. The drop-forging operation bends the strip into a circular band and at the same time forms a circumferentially extending channel in the band.
This procedure has several drawbacks. To begin with, the surface of the strip is damaged during drop-forging and requires time-consuming repair work. Furthermore, the channel-like shape of the circular band precludes the use of a slip joint for connecting the ends of the band to one another and these must be welded, brazed or soldered to each other, which are all operations difficult to perform on a concave or convex surface of a circular strip of metal. In addition, engraving becomes a difficult matter because it must be carried out after drop-forging when the surfaces to be engraved are curved.
In view of the above, it would be desirable to replace the drop-forging operation. However, this requires a metal forming tool capable of forming a channel in sheet material.
Various types of metal forming tools are known. Thus, U.S. Pat. No. 74,601 discloses pliers for bending sheet metal. The pliers have a hollow or concave jaw which cooperates with a corrugated or ribbed jaw.
U.S. Pat. No. 978,430 shows a tool for forming dental crowns. The tool comprises a concave jaw and a convex jaw which carry tooth-like dies for shaping a crown to final form.
U.S. Pat. No. 2,556,538 teaches a tool for repairing automobile moldings. The tool includes one jaw provided with a channel or gutter and another jaw provided with a shaping or molding rib.
U.S. Pat. No. 2,583,625 illustrates a tool for crimping tubular members, such as electrical terminals, onto electrical connectors. The tool has an indentor jaw with alternate depressions and protrusions, and two of the protrusions function as forming elements. The tool also has a nest jaw provided with alternate depressions and protrusions, and two of the depressions cooperate with the forming protrusions on the indentor jaw to crimp tubular members.
U.S. Pat. No. 2,637,231 discloses tube bending pliers. The two jaws of the pliers are formed with complementary, part-cylindrical, V-shaped grooves.
U.S. Pat. No. 2,828,780 shows wire forming pliers. One jaw of the pliers is provided with a die slot while the other jaw is provided with a forming projection which forces the free end of a wire into the die slot so as to shape the end of the wire.
U.S. Pat. No. 3,597,775 teaches a tool for making sinkers to be used with a fishing line. Each of the jaws has alternating depressions and protrusions, and two of the protrusions on one jaw cooperate with two of the depressions on the other jaw. The protrusions which cooperate with the depressions respectively function to form a groove in a sinker and to open a sinker.
U.S. Pat. No. 3,680,351 illustrates pliers for producing dilations in a branch pipe to be connected to a main pipe. One jaw of the pliers is provided with a hole and the other jaw of the pliers is provided with a projection which is arranged to enter the hole.
U.S. Pat. No. 3,956,950 discloses a tool for forming eyes on electrical wire. The tool comprises a first elongated jaw having a semicircular, longitudinally extending passage with spaced, transversely extending grooves for wires of different size. The tool further comprises a second elongated jaw of truncated configuration designed to cooperate with the first jaw.
U.S. Pat. No. 4,739,918 shows a tool for producing raised dimples in header plates. The tool includes two jaws, and one of the jaws has an end face provided with a part-spherical recess while the other jaw has a projection with a part-spherical end. The recess is designed to receive the part-spherical end of the projection.
U.S. Pat. No. 5,084,935 teaches a multipurpose, pliers-like tool for use in dentistry. Among the many features of the tool are two pairs of complementary male and female corrugating elements, a wire bending arrangement including an elongated groove and an elongated rib receivable in the groove, and a channel which can receive, in part, the free end of a cone.
French Patent No. 669,598 illustrates a tool having a first jaw with a wide, arcuate channel and a second jaw with a narrow groove.
Swiss Patent No. 44,706 discloses a tool with two sets of dies. Each die is formed with an arcuate groove.
Finally, Italian Patent No. 507,980 shows a pliers-like tool in which each jaw is again provided with an arcuate groove.
None of the above tools is designed to form a channel in sheet stock and, at the same time, impart longitudinal curvature to the sheet to provide an outwardly-convex band configuration.